[data from a 2.4 GHz Pentium 4 Xeon (Northwood)]

PERFCTR INIT: vendor 0, family 15, model 2, stepping 4, clock 2392322 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 276 cycles
PERFCTR INIT: rdtsc cost is 84.4 cycles (5680 total)
PERFCTR INIT: rdpmc cost is 148.1 cycles (9760 total)
PERFCTR INIT: rdmsr (counter) cost is 251.0 cycles (16340 total)
PERFCTR INIT: rdmsr (escr) cost is 165.8 cycles (10892 total)
PERFCTR INIT: wrmsr (counter) cost is 848.8 cycles (54600 total)
PERFCTR INIT: wrmsr (escr) cost is 920.3 cycles (59176 total)
PERFCTR INIT: read cr4 cost is 4.3 cycles (556 total)
PERFCTR INIT: write cr4 cost is 252.6 cycles (16444 total)
PERFCTR INIT: rdpmc (fast) cost is 60.0 cycles (4116 total)
PERFCTR INIT: rdmsr (cccr) cost is 166.9 cycles (10960 total)
PERFCTR INIT: wrmsr (cccr) cost is 872.5 cycles (56120 total)
perfctr: driver 2.3.11, cpu type Intel Pentium 4 Model 2 at 2392322 kHz